Is it possible to have dynamic rules with jquery validation?

Question

I got three fields, two inputs text and between them a select. If one of the first two is filled in the other becomes mandatory. The problem is that when a single value, in the latter case, of the select is filled the three become mandatory.

It is possible to have dynamic rules with this plugin, ie when checking the value of select make the third field mandatory?

HTML

<div id="msgErros"></div>
<form>
    <label for="tempoInicial">Tempo Inicial</label>
    <input type="text" name="filtro.tempoInicial" size="8" value="" id="tempoInicial" class="tempo" />
    <br />
    <label for="operadorTempo">Operador de Tempo</label>
    <select name="filtro.valorOperadorTempo" id="operadorTempo" class="tempo">
        <option value="">-- Selecione --</option>
        <option value="1">&gt; - Maior</option>
        <option value="2">&lt; - Menor</option>
        <option value="3">Entre</option>
    </select>
    <br />
    <label for="tempoFinal">Tempo Final</label>
    <input type="text" name="filtro.tempoFinal" size="8" value="" id="tempoFinal" />
    <br />
    <button>Enviar</button>
</form>

Javascript

$.validator.addMethod("skip_or_fill_minimum", function (value, element, options) {
    var $fields = $(options[1], element.form),
        $fieldsFirst = $fields.eq(0),
        validator = $fieldsFirst.data("valid_skip") ? $fieldsFirst.data("valid_skip") : $.extend({}, this),
        numberFilled = $fields.filter(function () {
            return validator.elementValue(this);
        }).length,
        isValid = numberFilled === 0 || numberFilled >= options[0];

    // Store the cloned validator for future validation
    $fieldsFirst.data("valid_skip", validator);

    // If element isn't being validated, run each skip_or_fill_minimum field's validation rules
    if (!$(element).data("being_validated")) {
        $fields.data("being_validated", true);
        $fields.each(function () {
            validator.element(this);
        });
        $fields.data("being_validated", false);
    }
    return isValid;
}, jQuery.validator.format("Please either skip these fields or fill at least {0} of them."));

$("form").validate({
    errorContainer: "#msgErros ul",
    errorLabelContainer: "#msgErros",
    wrapper: "li",
    rules: {
        "filtro.tempoInicial": {
            skip_or_fill_minimum: [2, ".tempo"]
        },
            "filtro.valorOperadorTempo": {
            skip_or_fill_minimum: [2, ".tempo"]
        }
    },
    groups: {
        tempos: "filtro.tempoInicial filtro.valorOperadorTempo"
    },
    onfocusout: function (element, event) {
        var classeCSSElemento = $(element).attr("class");
        var classeCSSElementoIndefinida = typeof classeCSSElemento === "undefined";
        if (classeCSSElementoIndefinida || (!classeCSSElementoIndefinida && !classeCSSElemento.contains("tempo"))) {
            $.validator.defaults.onfocusout.call(this, element, event);
        }
    }
});

Fiddle

Answer 1

It is possible to add and remove validation rules dynamically, as indicated by this response in SOEN: https://stackoverflow.com/a/4878858/195417

I am currently limited to internet, please check if this solves your problem... I can’t see the documentation to be sure.

Answer 2

It is possible to make this logic much simpler. Just add the following rules:

rules: {
    "filtro.tempoInicial": {
        required: function(element) {
            return $("#operadorTempo").val() == 3
                   || $('#tempoFinal').val() == '';
      }
    },
    "filtro.valorOperadorTempo": {
        required: true
    },
    "filtro.tempoFinal": {
        required: function(element) {
            return $("#operadorTempo").val() == 3 
                   || $('#tempoInicial').val() == '';
        }
    }
},

You don’t need that additional validator.

Functional demo in Jsfiddle